Effect of Rest Interval on Isokinetic Muscle Recovery in Children and Adolescents

Abstract

Adequate between-set rest intervals (RI) are necessary in order to offset the detrimental effects of fatigue during resistance training (RT). The acute effects of different between-set RI on muscle fatigue using isokinetic muscle actions have been studied in young and older men and women. However, children appear to recover from physical exertion faster than adults and adolescents. PURPOSE: To compare the effect of two different between set RI of isokinetic knee extension exercise on Peak Torque (PT), Total Work (TW), and Blood Lactate (BLa) between children and adolescents. METHODS: 18 children (11.1 ± 0.52 yrs) and 18 adolescents (15.8 ± 0.49 yrs) performed 3 sets of 10 unilateral isokinetic knee extension repetitions at 60°/s. The between set RI were 1 and 2 minutes and were counterbalanced across 2 testing days, separated by a minimum of 72 hours. Pubertal stage was determined according to Tanner and Whitehouse (1976). RESULTS: Bla was significantly higher than baseline after 1 min (1.04 ± 0.23 to 2.55 ± 0.47 mM) and 2 min (1.05 ± 0.20 to 2.58 ± 0.47 mM) RI for the children group, and after 1 min (1.17± 0.18 to 6.59 ± 1.07 mM) and 2 min (1.18 ± 0.17 to 6.03 ± 0.84 mM) RI for the adolescents group. However, after exercise, Bla was significantly higher in the adolescents as compared to the children in both RI. Results from PT and TW were as follows:TABLECONCLUSION: These results suggest that adolescents exhibit the capacity to produce greater muscular force, and as a consequence may develop a higher level of fatigue than children. Also, lower BLa suggests that children's true advantage may decrease in the shorter delay between the onset of exercise or its completion and the peaking of metabolites in the blood, allowing the recovery process to initiate earlier.